Several types of building blocks for use by children have already been proposed. For example, U.S. Pat. No. 3,854,237 shows a block having light sides including a half cube section and dowels to secure the blocks together. This block, although interesting, is probably not suitable for very young children who are just beginning to develop motor coordination: they would most likely be frustrated in trying to put the dowels into their respective holes. Also, the block does not have a balanced shape.